Imaging description

A 22-month-old female presented with a history of vomiting and a palpable right abdominal mass. An abdominal ultrasound (not shown) and an MRI of the abdomen (Fig. 64.1) demonstrated a large mass involving the right kidney, with distortion of the pelvicalyceal system. In addition a large tumor thrombus was noted in the right renal vein, extending into the inferior vena cava (IVC) to the level of the mid liver with marked dilatation of these vessels. The tumor thrombus also extended into the left renal vein, up to the renal hilum (Fig. 64.1). A renal biopsy confirmed the diagnosis of a Wilms’ tumor (WT).

Importance

WT is the most common renal neoplasm in children, with 95% of cases occurring between 2 and 5 years of age. Five to seven percent of children have bilateral disease with 7% of cases being multicentric (Fig. 64.2). Nephrogenic rests, which are thought to be precursors of WT, are seen in 1% of neonates and it is believed that only 1% of these transform into WT. Histologically, WTs are of triphasic cell lineage comprising blastemal, stromal, and epithelial cells and about 7% are anaplastic. Favorable histology WT have absence of anaplasia, have a better prognosis, and are more responsive to chemotherapy. Unfavorable histology WTs exhibit anaplasia, are chemotherapy resistant, and are associated with an increased risk of recurrence.